Time traveling through nuclear history

You knock on the door of the researcher's lab, and his student opens it, greeting you. You ask the student what they're studying here. He says that his tutor has a theory that objects are made up of smaller particles. You recognize this "tutor" as the famous philosopher Leucippus from your studies, and his student as Democritus. You think that they might have uranium samples in their lab or might be able to get you into the mines.

What do you do?